In U.S. Pat. No. 4,163,787, cyano(6-(substituted pyridinyl)methyl esters of 3-(2,2-dihaloethenyl)-2,2-dimethylcyclopropane carboxylic acids, their preparation and their utility as insecticides are taught. One of the drawbacks to the commercial use of these compounds is the cost of their preparation.
In the patent, the compounds are prepared by the reaction of an appropriate cyano(6-(substituted phenoxy)-2-pyridine)methanol with a 3-(2,2-dihaloethenyl)-2,2-dimethylcyclopropane carboxylic acid halide in the presence of a solvent and a hydrogen halide acceptor.
The pyridine methanol reactant is prepared by the reaction, at room temperature, of an appropriate 6-(substituted phenoxy)picolinaldehyde with an excess of an alkali metal cyanide in the presence of an alkali metal bisulfite and water. While the process as taught by U.S. Pat. No. 4,163,787 gives the desired product, other more economical methods of preparation are being sought.